The present invention relates to a frame for the display of pictures. Such frame may be an ordinary picture frame but the invention is preferably used in connection with a so-called sheet exchanger or picture exchanger as disclosed e.g. in U.S. Pat. No. 4,879,825. Briefly, such an exchanger comprises a housing having a display window in which a picture or sheet of a stack of sheets is exhibited. A slider may be reciprocated relative to the housing in a direction parallel to the window and activates an exchange mechanism by which the stack is cyclically rearranged. Such an apparatus stores a relatively great number of pictures, in particular photographic prints, but may also be used as a hanging frame or as a display stand. In the latter case, the housing is to be provided with a stand or prop.
A sheet exchanger having a prop is disclosed in U.S. Pat. No. 4,798,015. The prop extends under an angle almost diagonally with respect to the outer edges of the substantially rectangular housing and is connected to the housing by means of a hinge about which the prop may be pivoted into its operative position defined by stop lock means. The term "stop lock" as used herein defines a positive arresting of the prop when unfolded from the frame. The design is such that the frame defines the same angle with a table or like support when it is in upright and when it is in sidewise position. When the prop is not used it may be folded back into a complementary housing recess. A complementary recess for accomodation of a triangular frame prop is also disclosed in Swiss patent 456 875. Another sheet exchanger having a prop which may be pivoted relative to the housing about two axes is disclosed in U.S. Pat. No. 4,376,348.
U.S. Pat. No. 3,343,777 discloses a display stand provided with a prop. The prop is hinged to a support member which is pivotably mounted on the rear side of a frame member. The pivotable support member may be turned into any position, and the angle between the frame member and the prop may be arbitrarily adjusted to the convenience of the user.
Another frame provided with a prop is disclosed in British patent 1,073,651. The prop is integrally molded from plastics material. It comprises a hub portion to be mounted on the frame back and a prop portion connected to the hub portion by means of a hinge formed by a notch between hub and prop. The notch is triangular in cross section so as to define a stop which limits the angle between frame and prop. As the frame is rectangular but not square, the angle between the frame and a supporting surface is different for up-right and sidewise position when the prop is positioned by the stop.
German patent 150994 discloses a frame having a prop system basically similar to that of British patent 1,073,651.